4 HCIWhat happens when a human and a computer get together to perform a taskTaskWrite a documentPlan a budgetDesign a presentationPlay a video gameNot a task..Goof off (obviously)May 18, 2010IAT 334

5 Why is this important?Computers (in one way or another) affect every person in societyIncreasing % use computers in work, at home in the road…Product success depends on ease of useMay 18, 2010IAT 334

8 Goals of System EngineeringFunctionalityTasks and sub-tasks to be carried outReliabilityMaintaining trust in the systemStandardization, integration, consistency and portabilitySchedules and budgetsAdhering to timelines and expenseHuman factors principles and testing reduces costsMay 18, 2010IAT 334

15 Two Crucial Errors Assume all users are alikeAssume all users are like the designerMay 18, 2010IAT 334

16 Another Crucial Error Have the user design it!Users bring vital knowledge to design:They know a lot about the problemThey know a lot about the current toolsThey typically know very little about designMay 18, 2010IAT 334

53 Task Analysis Analyzing how people do their jobsGo to their environmentLearn about, analyze and describe their tasksExamine users’ tasks to better understand what they need from interface and how they will use itJan 13, 2011IAT 334

54 Task Analysis Gather data about what users need to do or accomplish…then…Represent data for interpretation and use in design decisionsJan 13, 2011IAT 334

55 Information to be GatheredInformation about usersDescription of environmentwhere the tasks will be performedMajor goals of the jobwhat will result in a successful end state?User preferences & needsbefore they even start: coffee, pen, notebook, log sheets…Jan 13, 2011IAT 334

58 Information to be GatheredTasks & Subtasks:PhysicalCognitiveCommunicationConditions under which these tasks are doneResults/outcomes of tasksRequirements to perform task:InformationCommunication with othersEquipmentJan 13, 2011IAT 334

59 1. Observation Watch users do what they do Record with videotapeTypically from a distanceRecord with videotapeMay require coding video laterTake lots of notes, sketchesFocus on specific task-relevant behaviors in notes, but later convert to abstract subtasksJan 13, 2011IAT 334

60 2. Interviews Engage the user more than just watchingStructured interviewsEfficient, but requires trainingUnstructuredInefficient, but requires no trainingSemi-structuredGood balanceOften appropriateJan 13, 2011IAT 334

61 3. Ethnography Deeply contextual inquiry “Live among” the users“Wallow in the data”“Live among” the usersUnderstanding the full complexity of behavior, in its complete social contextNote: Techniques based in sociology and anthropology--the study of humansJan 13, 2011IAT 334

63 5. Focus Groups Structured Interview with groups of individuals3 to 10 personsUse several different groups with different roles or perspectivesManage the interactionAvoid few people dominating the discussionFocus on preferences and views, not performanceRelatively low cost, quick way to learn a lotAudio or video record, with permissionJan 13, 2011IAT 334

64 6. Competitive Products Looking for both good and bad ideasFunctionalityUI styleWhy are they successful or unsuccessful?What does successful really mean?(Note: Successful does not equal usable)Jan 13, 2011IAT 334

81 Generalizability Does knowledge of one UI apply to others?Cut and paste in many appsDoes knowledge of one aspect of a UI apply to rest of the UI?File browsers in MacOS/ WindowsAid: UI Developers guidelinesJan 20, 2011IAT 334

82 Consistency Similar ways of doing tasksinteractingoutputscreen layoutIs this always desirable for all systems, all users?Jan 20, 2011IAT 334

85 Multithreading Two types Concurrent Interleavedinput to multiple tasks simultaneouslyInterleavedmany tasks, but input to one task at a timeJan 20, 2011IAT 334

86 Task migratabilityAbility to move performance of task to entity (machine or person) that can do it betterEg. AutopilotSpellcheckingWhen is this good? Bad?User in control when human decisions are requiredJan 20, 2011IAT 334

90 ObservabilityCan user determine internal state of system from observable state?Browsabilityexplore current state (without changing it)Reachabilitynavigate through observable statesPersistencehow long does observable state persist?Jan 20, 2011IAT 334

91 Recoverability Ability to continue to a goal after recognizing errorDifficulty of Recovery procedure should relate to difficulty of original taskForward Recoverabilityability to fix when we can’t undo?Backward Recoverabilityundo previous error(s)Jan 20, 2011IAT 334

92 Responsiveness Rate of communication between user and systemResponse timetime for system to respond in some way to user action(s)Stability principleresponse time, rate should be consistentAs computers have gotten better, required computer response has gotten shorterJan 20, 2011IAT 334

100 Iterate on Design Redesign system Be prepared to abandon bad ideas!!in light of initial user impressionspay attention to common complaintsBe prepared to abandon bad ideas!!It’s just an idea, not a measure of your worth!Feb 3, 2011IAT 334

101 Idea CreationHow do we create and develop new interface ideas and designs?Ideas come fromImaginationAnalogyObservation of current practiceObservation of current systemsBorrow from other fieldsAnimationTheatreInformation displaysArchitecture...Feb 3, 2011IAT 334

102 Interface MetaphorsMetaphor - Application of name or descriptive term to another object which is not literally applicableUse: Natural transfer - apply existing knowledge to new, abstract tasksProblem: May introduce incorrect mental modelFeb 3, 2011IAT 334

103 Mental Models What models of the world are the users using?Two Classes:Functional model“Press the accelerator once, then turn the key”Structural modelOK, why do we do that?Feb 3, 2011IAT 334

104 Another example... Functional model Structural model“Go north on King George, Cross the Pattullo, Turn left at 10th Ave, Turn right at Kingsway, go 4.5km”Structural modelWhat location??Feb 3, 2011IAT 334

109 Guidelines for Design 1. Provide a good conceptual modelUser has mental model of how things workBuild design that allows user to predict effects of actions2. Make things visibleVisible affordances, mappings, constraintsRemind person of what can be done and how to do itFeb 3, 2011IAT 334

125 CL Design Goals Consistency Good naming and abbreviationsSyntax, orderGood naming and abbreviationsDoing your homework in design can help alleviate some of the negativesFeb 10, 2011IAT 334

126 Consistency Provide a consistent syntaxIn general: Have options and arguments expressed the same way everywhereUNIX fails here because commands were developed by lots of different people at different organizationsNo guidelines providedFeb 10, 2011IAT 334

137 Presentation SequenceChoicesAlphabeticalGroup related itemsFrequently used firstMost important firstConventional order (MTWRF)Don’t change the order on the fly!Feb 10, 2011IAT 334

138 Direct ManipulationContinuous visibility of the objects and actions of interestRapid, incremental actionsReversibility of all actions to encourage experimentationSyntactic correctness of all actions—every action is syntactically legalReplacement of command language syntax by direct manipulation of object of interestFeb 10, 2011IAT 334

141 DM Essence Representation of reality that can be manipulatedThe user is able to apply intellect directly to the taskDon’t have to name things, just touch themThe tool itself seems to disappearFeb 10, 2011IAT 334

142 Direct Manipulation is LocalityDM Relies on a primary geometric organizationItems located nearby are frequently edited togetherThe words in a sentenceA column of numbers in a spreadsheetLess related -> Less local -> Less DM!Feb 10, 2011IAT 334

145 User ModelingIdea: If we can build a model of how a user works, then we can predict how s/he will interact with the interfacePredictive modelingMany different modeling techniques existFeb 24, 2011IAT 334

147 Power Law of Practice Tn = T1n-aTn to complete the nth trial is T1 on the first trial times n to the power -a; a is about .4, between .2 and .6Skilled behavior - Stimulus-Response and routine cognitive actionsTyping speed improvementLearning to use mousePushing buttons in response to stimuliNOT learningFeb 24, 2011IAT 334

149 Fitts’ LawModels movement times for selection (reaching) tasks in one dimensionBasic idea: Movement time for a selection taskIncreases as distance to target increasesDecreases as size of target increasesFeb 24, 2011IAT 334

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